Ball launchers are used as practice aids in many different sports including baseball, football, tennis, and volleyball and in other "ball" sports. It is important in practice to present or deliver a ball to a player under selected simulated game conditions so that he may practice responsive manipulation of the ball. It also important in practice that the ball be delivered repeatedly under the selected conditions identically each time so that the player or pupil practicing can concentrate on mastering his techniques of responding to the simulated conditions without worry about a change in those conditions.
Ball launchers for the various types of balls used in most common sports are available. In some the impulse force to launch the ball is delivered by the impact of a spring-loaded member against the ball positioned for launching. In others the ball may be placed in a catapult type mechanism for launching; in still others the ball is delivered through a tube into a space between two or more rapidly rotating wheels set at a distance from each other just slightly less than the ball diameter. Other types of launching machines operate on compressed gas and "shoot" the balls from a long tube in a manner similar to a gas operated pellet or BB gun.
Launching machines of the same types mentioned are exemplified by those of the following patents: U.S. Pat. No. 4,714,069 for a Volleyball Setting Machine by Harold C. Ulrich; U.S. Pat. No. 5,062,646 for a Volleyball Training Apparatus by Michael A. Crist; U.S. Pat. No. 5,107,820 for a Ball-Throwing Device For Tennis Balls by Werner Salansky; U.S. Pat. No. 4,254,755 for Ball Training Machine Useful In Practicing The Game of Volleyball by Steven R. Morgan et al.; U.S. Pat. No. 4,323,048 for Ball Shooting Machine For Volleyball Practice by Retsuo Saito et al.
Prior machines of the types shown in those patents may not be easily transportable, or do not impart a human-like acceleration impulse to the ball, or do not accurately repeat ball delivery characteristics or may not be easily adjustable to impart different ball delivery characteristics.